In connection with so-called jump-lifts, the elevator hoistway is taken into use already before the full length of the elevator hoistway has been completed. The top part of the elevator hoistway is constructed at the same time as an elevator car moving in the already completed bottom part of the elevator hoistway serves people on the lower floors of the building. In jump-lifts, the elevator car moving in the lower part of the elevator hoistway is supported and moved during the construction-time use suspended on hoisting ropes that are supported by a supporting platform in the elevator hoistway, which ropes are moved with a hoisting machine that is usually supported on the supporting platform. Installation work is done in the parts of the elevator hoistway above this supporting platform. When the part of the elevator hoistway under construction above the supporting platform has reached a sufficient stage of readiness, the completed part of the elevator hoistway can be taken into use. In this case a jump-lift is performed, wherein the supporting platform is lifted to a higher position in the elevator hoistway, thus extending the operating range of the elevator car upwards. A worksite crane in use in the construction of the building can, for example, be used for the lifting. Alternatively it has been possible to move the machine room platform that is being supported in the lifting on a support structure in the hoistway above the machine room platform.
When the elevator hoistway has reached its final height, the machine room platform has usually been removed from the elevator hoistway and the final hoisting machine of the elevator has been brought into a machine room built at the end of the elevator hoistway. As a conclusion to the installation method the construction-time roping is often removed and the elevator is reeved again with the final roping. One solution according to prior art is described in publication WO 2010100319 A1.
A problem in prior-art solutions has been that the hoisting arrangements needed for lifting the supporting platform are very space-consuming, are complex and are not sufficiently quick to use. More particularly the support points needed for shifting and positioning the machine room platform are difficult to arrange. It would not be desirable to separately arrange numerous support points in a building. It has been noticed that the difficulty of finding support points that are sufficiently stable and durable effectively limits the maximum height to which a jump-lift can, with a reasonable work input, reach. A worksite crane must sometimes be used for shifting the machine room platform, because the aforementioned problems make other solutions so awkward. Another problem has been, generally speaking, the demanding installation environment, which has set numerous practical challenges, which are connected to the smooth-running and safety of the installation and to the durability of structures. These are, inter alia, the space usage and complexity of the hoisting arrangement of the machine room platform, the center of mass and stability of the machine room platform during the lifting and while in position, the center of mass and stability of the support arrangement to be used for the lifting during the lifting and while in position, the placement producing a suitable balance of the support locking mechanism, the cramped layout of the machine room platform, suitable hoisting devices, the dimensioning of the hoisting machine for the final travel height, routing of the ropes with adequate run clearances, correct configuration of the rope length, the need for safe and spacious working space and position. These numerous variables that must be taken into account affect each other directly or indirectly and their overall effect is that the structure easily becomes complex and heavily built, and requires a lot of space. Taking these challenges into account, there has been a need to further simplify the support structure to be lifted in a jump lift and to reduce the weight to be lifted in a jump lift. Likewise, there has been a need to further develop the safety and speed of the method.